San Francisco Tides

Time Event Value Units
01:12 am Low Tide 1.23 ft
04:10 am Slack
06:42 am Max Flood 1.1 kt
08:24 am High Tide 3.62 ft
09:21 am Slack
11:44 am Max Ebb -1.1 kt
12:05 pm Low Tide 3.17 ft
02:22 pm Slack
04:56 pm Max Flood 1 kt
06:38 pm High Tide 5.6 ft
06:52 pm Slack
11:34 pm Max Ebb -2.4 kt
What day is the longest?
Why are there 2 tides per day?
Why doesn't Slack = High/Low Tide?
Why can you ride a flood but not an ebb?